:root {
  --surface:#17171e;--panel:#1e1e28;--border:#2a2a38;
  --accent:#6ee7b7;--accent2:#818cf8;--accent3:#f472b6;
  --text:#e2e8f0;--muted:#64748b;--toolbar-w:76px;
  /* canvas-theme-driven */
  --canvas-bg:#0f0f13; --grid-dot:rgba(255,255,255,.10);
}
/* canvas themes */
[data-theme="white"]  {--canvas-bg:#ffffff; --grid-dot:rgba(0,0,0,.13)}
[data-theme="cream"]  {--canvas-bg:#faf6e9; --grid-dot:rgba(80,60,30,.18)}
[data-theme="slate"]  {--canvas-bg:#1f2937; --grid-dot:rgba(255,255,255,.12)}
[data-theme="black"]  {--canvas-bg:#000000; --grid-dot:rgba(255,255,255,.10)}

*{margin:0;padding:0;box-sizing:border-box}
body{background:#0f0f13;font-family:'Syne',sans-serif;color:var(--text);height:100vh;overflow:hidden;display:flex;flex-direction:column;user-select:none}

/* ── TOPBAR ── */
#topbar{height:50px;background:var(--surface);border-bottom:1px solid var(--border);display:flex;align-items:center;padding:0 14px;gap:6px;z-index:30;flex-shrink:0}
.logo{font-weight:800;font-size:15px;letter-spacing:-0.5px;background:linear-gradient(135deg,var(--accent),var(--accent2));-webkit-background-clip:text;-webkit-text-fill-color:transparent;margin-right:6px}
.sep{width:1px;height:24px;background:var(--border)}
.top-btn{height:32px;padding:0 11px;border-radius:6px;border:1px solid var(--border);background:transparent;color:var(--muted);font-family:'DM Mono',monospace;font-size:11px;cursor:pointer;transition:all .15s;display:flex;align-items:center;gap:6px;white-space:nowrap;position:relative}
.top-btn:hover{color:var(--text);border-color:var(--accent);background:rgba(110,231,183,.06)}
.top-btn:focus-visible{outline:2px solid var(--accent);outline-offset:1px}
.top-btn.danger:hover{color:#f87171;border-color:#f87171;background:rgba(248,113,113,.06)}
.top-btn svg{width:14px;height:14px}
.top-btn.icon-only{padding:0;width:32px;justify-content:center}
.top-btn .caret{width:8px;height:8px;margin-left:1px}
.spacer{flex:1}
#stroke-info{font-family:'DM Mono',monospace;font-size:11px;color:var(--muted)}
#board-name{background:transparent;border:1px solid transparent;border-radius:4px;color:var(--text);font-family:'Syne',sans-serif;font-size:13px;font-weight:600;padding:2px 8px;max-width:200px;outline:none}
#board-name:hover{border-color:var(--border)}
#board-name:focus{border-color:var(--accent);background:var(--panel)}

/* ── DROPDOWN ── */
.dropdown{position:absolute;top:38px;background:var(--surface);border:1px solid var(--border);border-radius:8px;padding:6px;min-width:160px;display:none;z-index:50;box-shadow:0 8px 24px rgba(0,0,0,.4)}
.dropdown.show{display:block}
.dd-item{display:flex;align-items:center;gap:8px;padding:8px 10px;border-radius:5px;color:var(--text);font-family:'DM Mono',monospace;font-size:11px;cursor:pointer}
.dd-item:hover{background:var(--panel);color:var(--accent)}
.dd-item svg{width:14px;height:14px;flex-shrink:0}
.dd-section{font-family:'DM Mono',monospace;font-size:9px;color:var(--muted);padding:6px 10px 2px;text-transform:uppercase;letter-spacing:.05em}

/* ── MAIN ── */
#main{display:flex;flex:1;overflow:hidden;flex-direction:column}
#work{display:flex;flex:1;overflow:hidden}

/* ── TOOLBAR ── */
#toolbar{width:var(--toolbar-w);background:var(--surface);border-right:1px solid var(--border);display:flex;flex-direction:column;align-items:center;padding:6px 0;gap:1px;z-index:30;overflow-y:auto;transition:box-shadow .2s}
#toolbar.floating{position:fixed;border-radius:14px;border:1px solid var(--border);box-shadow:0 10px 40px rgba(0,0,0,.5);max-height:calc(100vh - 100px)}
#toolbar-drag{width:100%;height:18px;display:flex;align-items:center;justify-content:center;cursor:grab;color:var(--muted);flex-shrink:0;opacity:.5;transition:opacity .15s}
#toolbar-drag:hover{opacity:1;color:var(--accent)}
#toolbar-drag:active{cursor:grabbing}
#toolbar-drag svg{width:18px;height:14px}
#toolbar.floating #toolbar-drag{opacity:.85;color:var(--accent2)}
#toolbar::-webkit-scrollbar{width:0}
.tb-group{display:flex;flex-direction:column;align-items:center;gap:1px;padding:4px 0;width:100%;border-bottom:1px solid var(--border)}
.tb-group:last-child{border-bottom:none}
.tb-label{font-family:'DM Mono',monospace;font-size:8px;color:var(--muted);text-transform:uppercase;letter-spacing:.08em;margin-bottom:2px;opacity:.6}
.tool-btn{width:50px;height:42px;border-radius:8px;border:1px solid transparent;background:transparent;color:var(--muted);cursor:pointer;display:flex;align-items:center;justify-content:center;flex-direction:column;gap:1px;font-size:9px;font-family:'DM Mono',monospace;transition:all .12s;flex-shrink:0}
.tool-btn svg{width:18px;height:18px}
.tool-btn:hover{color:var(--text);background:var(--panel)}
.tool-btn:focus-visible{outline:2px solid var(--accent);outline-offset:-2px}
.tool-btn.active{color:var(--accent);background:rgba(110,231,183,.1);border-color:rgba(110,231,183,.3)}
.tool-btn.active.erase-mode{color:var(--accent3);background:rgba(244,114,182,.1);border-color:rgba(244,114,182,.3)}
.tool-btn.active.hand-mode{color:var(--accent2);background:rgba(129,140,248,.12);border-color:rgba(129,140,248,.3)}
/* expandable shape section */
.shape-extra{display:none;flex-direction:column;align-items:center;gap:1px;width:100%;padding-top:2px;border-top:1px dashed var(--border);margin-top:2px;animation:expand .15s ease}
.shape-extra.show{display:flex}
@keyframes expand{from{opacity:0;transform:translateY(-4px)}to{opacity:1;transform:translateY(0)}}
.shape-expand svg{transition:transform .15s}
.shape-expand.open svg{transform:rotate(180deg)}

/* palette */
#palette{display:grid;grid-template-columns:repeat(2,1fr);gap:4px;padding:4px 0}
.color-dot{width:18px;height:18px;border-radius:50%;cursor:pointer;border:2px solid transparent;transition:all .12s;flex-shrink:0}
.color-dot:hover{transform:scale(1.2)}
.color-dot.active{border-color:#fff;transform:scale(1.15);box-shadow:0 0 0 2px var(--surface)}
.color-dot.custom{display:flex;align-items:center;justify-content:center;background:conic-gradient(#f87171,#fbbf24,#a3e635,#38bdf8,#c084fc,#f472b6,#f87171);position:relative;overflow:hidden}
.color-dot.custom input{position:absolute;inset:-4px;opacity:0;cursor:pointer;width:200%;height:200%;border:none;padding:0}

/* quick sizes */
#quick-sizes{display:flex;flex-direction:column;align-items:center;gap:5px;padding:4px 0}
.qs-btn{width:32px;height:24px;display:flex;align-items:center;justify-content:center;border-radius:4px;cursor:pointer;border:1px solid transparent;transition:all .12s}
.qs-btn:hover{background:var(--panel)}
.qs-btn.active{background:rgba(110,231,183,.1);border-color:rgba(110,231,183,.3)}
.qs-dot{background:var(--text);border-radius:50%}

#size-section{padding:4px 0;display:flex;flex-direction:column;align-items:center;gap:4px}
#size-slider{-webkit-appearance:none;appearance:none;writing-mode:vertical-lr;direction:rtl;width:4px;height:50px;background:var(--border);border-radius:2px;outline:none;cursor:pointer}
#size-slider::-webkit-slider-thumb{-webkit-appearance:none;width:13px;height:13px;border-radius:50%;background:var(--accent);cursor:pointer}
#size-val{font-family:'DM Mono',monospace;font-size:10px;color:var(--accent)}

/* ── CANVAS AREA ── */
#canvas-wrap{flex:1;position:relative;overflow:hidden;background:var(--canvas-bg);transition:background .2s;touch-action:none}
#viewport{position:absolute;top:0;left:0;width:100%;height:100%;transform-origin:0 0;z-index:1}
#object-layer{position:absolute;inset:0}
#object-layer.multi .resize-handle{display:none!important}
#grid{position:absolute;inset:0;pointer-events:none;z-index:0}
/* grid styles applied via data-grid attribute on html */
[data-grid="dots"]  #grid{background-image:radial-gradient(circle, var(--grid-dot) 1px, transparent 1px)}
[data-grid="lines"] #grid{background-image:linear-gradient(var(--grid-dot) 1px,transparent 1px),linear-gradient(90deg,var(--grid-dot) 1px,transparent 1px)}
[data-grid="ruled"] #grid{background-image:linear-gradient(var(--grid-dot) 1px,transparent 1px)}
[data-grid="none"]  #grid{background-image:none}

#board{position:absolute;inset:0;z-index:2;touch-action:none;width:100%;height:100%}

/* objects */
.obj{position:absolute;z-index:3;border:1.5px solid transparent;border-radius:8px;cursor:grab}
.obj:hover{border-color:rgba(129,140,248,.25)}
.obj.selected{border-color:var(--accent2);box-shadow:0 0 0 1px var(--accent2),0 8px 30px rgba(0,0,0,.4)}
.obj img{display:block;width:100%;height:100%;border-radius:6px;pointer-events:none}
.obj .mermaid-render,.obj .math-render{background:#fff;border-radius:6px;padding:14px;width:100%;height:100%;overflow:hidden;display:flex;align-items:center;justify-content:center}
.obj .mermaid-render svg{max-width:100%;max-height:100%}
.obj .math-render{color:#111;font-size:22px}
.obj .sticky{width:100%;height:100%;border-radius:6px;padding:14px;font-family:'Syne',sans-serif;font-weight:600;font-size:15px;color:#1a1a1a;outline:none;overflow:auto;line-height:1.4}
.obj .resize-handle{position:absolute;right:-7px;bottom:-7px;width:16px;height:16px;border-radius:50%;background:var(--accent2);border:2px solid var(--surface);cursor:nwse-resize;z-index:5;display:none}
.obj.selected .resize-handle{display:block}
.obj .obj-del{position:absolute;right:-9px;top:-9px;width:18px;height:18px;border-radius:50%;background:#f87171;border:2px solid var(--surface);color:#fff;cursor:pointer;z-index:5;display:none;align-items:center;justify-content:center;font-size:11px;line-height:1}
.obj.selected .obj-del{display:flex}
#cursor-ring{position:absolute;border-radius:50%;border:1.5px solid rgba(110,231,183,.7);pointer-events:none;z-index:50;transform:translate(-50%,-50%);display:none}
#marquee{position:absolute;border:1px solid var(--accent2);background:rgba(129,140,248,.12);z-index:10;pointer-events:none}

/* ── BOTTOM BAR ── */
#bottom-bar{position:absolute;bottom:54px;left:50%;transform:translateX(-50%);background:var(--surface);border:1px solid var(--border);border-radius:12px;padding:7px 14px;display:flex;align-items:center;gap:14px;z-index:20;font-family:'DM Mono',monospace;font-size:11px;color:var(--muted)}
#bottom-bar input[type=range]{-webkit-appearance:none;appearance:none;width:70px;height:4px;border-radius:2px;background:var(--border);outline:none;cursor:pointer}
#bottom-bar input[type=range]::-webkit-slider-thumb{-webkit-appearance:none;width:12px;height:12px;border-radius:50%;background:var(--accent2);cursor:pointer}
.zoom-btn{width:24px;height:24px;border-radius:5px;border:1px solid var(--border);background:transparent;color:var(--text);cursor:pointer;font-size:14px;display:flex;align-items:center;justify-content:center}
.zoom-btn:hover{border-color:var(--accent);color:var(--accent)}
.bb-group{display:flex;align-items:center;gap:8px}

/* ── STORAGE WARNING ── */
#storage-warn{position:absolute;bottom:110px;left:50%;transform:translateX(-50%);background:#7f1d1d;border:1px solid #f87171;color:#fee2e2;font-family:'DM Mono',monospace;font-size:11px;padding:8px 14px;border-radius:8px;z-index:60;display:none;align-items:center;gap:10px;max-width:90vw}
#storage-warn.show{display:flex}
#storage-warn button{background:transparent;border:1px solid #fca5a5;color:#fee2e2;border-radius:5px;padding:3px 9px;cursor:pointer;font-family:inherit;font-size:10px}
#storage-warn button:hover{background:rgba(252,165,165,.15)}

/* ── HINT (dismissible) ── */
#hint{position:absolute;top:12px;right:12px;background:var(--surface);border:1px solid var(--border);border-radius:8px;padding:8px 28px 8px 12px;font-family:'DM Mono',monospace;font-size:10px;color:var(--muted);line-height:1.7;z-index:20;opacity:.85}
#hint kbd{background:var(--panel);border:1px solid var(--border);border-radius:3px;padding:1px 5px}
#hint-close{position:absolute;top:4px;right:6px;background:transparent;border:none;color:var(--muted);cursor:pointer;font-size:14px;padding:2px;line-height:1}
#hint-close:hover{color:var(--accent3)}
#hint-toggle{position:absolute;top:12px;right:12px;width:28px;height:28px;border-radius:50%;background:var(--surface);border:1px solid var(--border);color:var(--muted);cursor:pointer;display:none;align-items:center;justify-content:center;z-index:20;font-family:'DM Mono',monospace;font-size:13px}
#hint-toggle:hover{color:var(--accent);border-color:var(--accent)}

/* ── PAGE STRIP ── */
#page-strip{height:46px;background:var(--surface);border-top:1px solid var(--border);display:flex;align-items:center;padding:0 14px;gap:6px;z-index:30;flex-shrink:0;overflow-x:auto}
#page-strip::-webkit-scrollbar{height:0}
.page-tab{height:30px;min-width:64px;padding:0 14px;border-radius:6px;border:1px solid var(--border);background:transparent;color:var(--muted);font-family:'DM Mono',monospace;font-size:11px;cursor:pointer;transition:all .15s;display:flex;align-items:center;justify-content:center;gap:4px;flex-shrink:0}
.page-tab:hover{color:var(--text);border-color:var(--accent)}
.page-tab.active{background:rgba(110,231,183,.1);color:var(--accent);border-color:rgba(110,231,183,.3)}
.page-add{width:30px;height:30px;border-radius:6px;border:1px dashed var(--border);background:transparent;color:var(--muted);font-size:16px;cursor:pointer;display:flex;align-items:center;justify-content:center;flex-shrink:0}
.page-add:hover{color:var(--accent);border-color:var(--accent)}
#page-info{margin-left:auto;font-family:'DM Mono',monospace;font-size:11px;color:var(--muted)}

/* ── PANELS (boards, settings) ── */
.panel-bg{display:none;position:fixed;inset:0;z-index:100;background:rgba(0,0,0,.6);align-items:center;justify-content:center}
.panel-bg.show{display:flex}
.panel{background:var(--surface);border:1px solid var(--border);border-radius:14px;padding:22px;width:480px;max-width:90vw;max-height:80vh;overflow-y:auto;position:relative}
.panel h3{font-size:16px;margin-bottom:12px}
.panel-close{position:absolute;top:14px;right:14px;width:28px;height:28px;border-radius:50%;background:transparent;border:1px solid var(--border);color:var(--muted);cursor:pointer;font-size:14px;display:flex;align-items:center;justify-content:center}
.panel-close:hover{color:#f87171;border-color:#f87171}

.board-item{display:flex;align-items:center;padding:10px 12px;border:1px solid var(--border);border-radius:8px;margin-bottom:6px;cursor:pointer;gap:12px;transition:all .15s}
.board-item:hover{border-color:var(--accent);background:rgba(110,231,183,.05)}
.bi-name{flex:1;font-weight:600;font-size:13px}
.bi-date,.bi-pages{font-family:'DM Mono',monospace;font-size:10px;color:var(--muted)}
.bi-del{width:24px;height:24px;border-radius:50%;border:1px solid var(--border);background:transparent;color:var(--muted);cursor:pointer;display:flex;align-items:center;justify-content:center;font-size:12px;flex-shrink:0}
.bi-del:hover{color:#f87171;border-color:#f87171}

/* settings panel */
.setting-row{margin-bottom:18px}
.setting-label{font-family:'DM Mono',monospace;font-size:10px;color:var(--muted);text-transform:uppercase;letter-spacing:.05em;margin-bottom:8px}
.setting-options{display:flex;gap:8px;flex-wrap:wrap}
.bg-swatch{width:46px;height:46px;border-radius:10px;cursor:pointer;border:2px solid var(--border);transition:all .15s;position:relative;overflow:hidden}
.bg-swatch.active{border-color:var(--accent);box-shadow:0 0 0 2px rgba(110,231,183,.2)}
.bg-swatch span{position:absolute;bottom:2px;left:0;right:0;text-align:center;font-family:'DM Mono',monospace;font-size:8px;color:rgba(255,255,255,.5);text-shadow:0 1px 2px rgba(0,0,0,.6)}
.bg-swatch[data-light="1"] span{color:rgba(0,0,0,.5);text-shadow:none}
.grid-swatch{width:60px;height:46px;border-radius:8px;cursor:pointer;border:2px solid var(--border);background-color:#1e1e28;background-size:10px 10px;display:flex;align-items:flex-end;justify-content:center;padding-bottom:2px;font-family:'DM Mono',monospace;font-size:9px;color:var(--muted);transition:all .15s}
.grid-swatch.active{border-color:var(--accent);color:var(--accent)}
.grid-swatch[data-style="dots"]{background-image:radial-gradient(circle,rgba(255,255,255,.4) 1px,transparent 1px)}
.grid-swatch[data-style="lines"]{background-image:linear-gradient(rgba(255,255,255,.3) 1px,transparent 1px),linear-gradient(90deg,rgba(255,255,255,.3) 1px,transparent 1px)}
.grid-swatch[data-style="ruled"]{background-image:linear-gradient(rgba(255,255,255,.3) 1px,transparent 1px)}
.grid-swatch[data-style="none"]{background-image:none}
.psens-opt{padding:8px 14px;border-radius:7px;border:2px solid var(--border);cursor:pointer;font-family:'DM Mono',monospace;font-size:11px;color:var(--muted);transition:all .15s;background:var(--panel)}
.psens-opt:hover{color:var(--text)}
.psens-opt.active{border-color:var(--accent);color:var(--accent);background:rgba(110,231,183,.08)}

/* modal (mermaid/math) */
#modal-bg{position:fixed;inset:0;background:rgba(0,0,0,.6);display:none;align-items:center;justify-content:center;z-index:110}
#modal{background:var(--surface);border:1px solid var(--border);border-radius:14px;padding:22px;width:520px;max-width:90vw}
#modal h3{font-size:16px;margin-bottom:4px}
#modal p{font-size:12px;color:var(--muted);margin-bottom:12px;font-family:'DM Mono',monospace}
#modal textarea{width:100%;height:160px;background:#0f0f13;border:1px solid var(--border);border-radius:8px;padding:12px;color:var(--text);font-family:'DM Mono',monospace;font-size:13px;resize:vertical;outline:none}
#modal textarea:focus{border-color:var(--accent)}
.modal-actions{display:flex;gap:8px;justify-content:flex-end;margin-top:14px}
.modal-btn{padding:8px 18px;border-radius:7px;border:1px solid var(--border);background:transparent;color:var(--text);cursor:pointer;font-family:'Syne',sans-serif;font-weight:600;font-size:13px}
.modal-btn.primary{background:var(--accent);color:#0f0f13;border-color:var(--accent)}
.modal-btn:hover{opacity:.85}
.preset-row{display:flex;gap:6px;margin-bottom:10px;flex-wrap:wrap}
.preset-chip{font-family:'DM Mono',monospace;font-size:10px;padding:4px 9px;border-radius:5px;border:1px solid var(--border);background:var(--panel);color:var(--muted);cursor:pointer}
.preset-chip:hover{color:var(--accent);border-color:var(--accent)}

/* AI assist row + text inputs */
.ai-row{display:flex;gap:8px;align-items:center;margin-bottom:10px}
.ai-tag{font-family:'DM Mono',monospace;font-size:10px;color:#0f0f13;background:linear-gradient(135deg,var(--accent),var(--accent2));padding:4px 8px;border-radius:5px;font-weight:700;flex-shrink:0}
#ai-prompt{flex:1;background:#0f0f13;border:1px solid var(--border);border-radius:7px;padding:8px 10px;color:var(--text);font-family:'DM Mono',monospace;font-size:12px;outline:none;min-width:0}
#ai-prompt:focus{border-color:var(--accent2)}
.ai-gen{padding:7px 14px;border-radius:7px;border:1px solid var(--accent2);background:rgba(129,140,248,.12);color:var(--accent2);cursor:pointer;font-family:'Syne',sans-serif;font-weight:600;font-size:12px;white-space:nowrap}
.ai-gen:hover{background:rgba(129,140,248,.22)}
.ai-gen:disabled{opacity:.6;cursor:default}
.text-input{width:100%;background:#0f0f13;border:1px solid var(--border);border-radius:7px;padding:8px 10px;color:var(--text);font-family:'DM Mono',monospace;font-size:12px;outline:none;margin-bottom:6px}
.text-input:focus{border-color:var(--accent)}